Documentation

When the cache is configured and enabled, every document read and parsed is serialized and stored in binary
form in the cache. When reading the same document again, it is just deserialized, no parsing is performed.

The cache is configured by a path pointing to a directory for storing the documents,
by a maximal time span in second for valid documents. After that time span, the documents are read again
and the cache is updated.
The flag contols, whether documents returning 404 or other errors will be cached.
If set, the cache is even activated for 404 (not found) responses, default is false.

The serialized documents can be compressed, e.g. with bzip, to save disk space and IO time.
The compression can be configured by Text.XML.HXT.Arrow.XmlState.withCompression